November 30, 2020

Basolateral amygdala to nucleus accumbens projections differentially mediate flexibility of sign- and goal-tracking rats

Rats rely on communication between basolateral amygdala (BLA) and nucleus accumbens (NAc) to express lever directed approach in a Pavlovian lever autoshaping (PLA) task that distinguishes sign- and goal-tracking rats. Sign-tracking rats inflexibly respond to cues even after the associated outcome is devalued, whereas goal-tracking rats adaptively suppress conditioned responding during outcome devaluation. Here, we sought to determine whether BLA-NAc communication in sign-trackers drives rigid appetitive approach that is insensitive to manipulations of outcome value. Using a chemogenetic disconnection design, we injected contralateral BLA and NAc core with inhibitory DREADD (hm4D-mcherry) or control (mcherry) constructs. To determine sign- and goal-tracking groups, we trained rats in five PLA sessions in which brief lever insertion predicts food pellet delivery. We sated rats on training pellets (devalued condition) or homecage chow (valued condition) prior to systemic clozapine injections (0.1 mg/kg) to disrupt communication between BLA and NAc during two outcome devaluation probe tests, in which we measured lever and foodcup approach. BLA-NAc chemogenetic disconnection promoted flexible lever approach in sign-tracking rats, but disrupted flexible food-cup approach in goal-tracking rats. We observed more lever directed approach in female rats, and stronger devaluation sensitivity of foodcup approach in male rats. Exploratory analyses suggest the devaluation sensitivity of lever directed approach unmasked by BLA-NAc disconnection is evident in male, but not female, rats, indicating the importance of including both sexes in future studies. Together these findings suggest rigid appetitive associative encoding in BLA-NAc of ST rats hinders the expression of flexible behavior when outcome value changes.

 bioRxiv Subject Collection: Neuroscience

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